Because it will be always possible to find a root cause out of your control, you can stop digging deeper once you have found such a cause. Now you have two choices:

You can simply act as if your root cause does not exist. That means: just ignore it. Imagine a world were exactly this fact is not a given. How would you behave then? Is this behavior really impossible because of your root cause, or did you just miss the opportunity?

Change the way you handle unbeatable root causes. Consider how you have adapted to the current situation, how you act in face of the problem. There is always the opportunity to act just differently, if you cannot get rid of an issue.